Investigation of optimal dose of early intervention to prevent posttraumatic stress disorder: A multiarm randomized trial of one and three sessions of modified prolonged exposure.

Background: Posttraumatic stress disorder (PTSD) is linked to a specific event, providing the opportunity to intervene in the immediate aftermath of trauma to prevent the development of this disorder. A previous trial demonstrated that trauma survivors who received three sessions of modified prolonged exposure therapy demonstrated decreased PTSD and depression prospectively compared to assessment only. The present study investigated the optimal dosing of this early intervention to test one versus three sessions of exposure therapy in the immediate aftermath of trauma.

Methods: Participants (n = 95) recruited from a Level 1 Trauma Center were randomly assigned in a 1.5:1.5:1 ratio in a parallel-group design to the three conditions: one-session exposure therapy, three-session exposure therapy, and assessment only. Follow-up assessments were conducted by study assessors blind to study condition.

Results: Mixed-effects model results found no significant differences in PTSD or depression symptoms between the control condition and those who received one or three exposure therapy sessions across 1-12-month follow-up assessment. Results indicate that the intervention did not interfere with natural recovery. Receiver operating characteristic curve analyses on the screening measure used for study inclusion (Predicting PTSD Questionnaire; PPQ) in the larger sample from which the treatment sample was drawn (n = 481) found that the PPQ was a poor predictor of likely PTSD at all follow-up time points (Area under the curve's = 0.55-0.62).

Conclusions: This likely impacted study results as many participants demonstrated natural recovery. Recommendations for future early intervention research are reviewed, including strategies to identify more accurately those at risk for PTSD and oversampling more severe trauma types.